Metal oxide negative electrodes for lithium-ion electrochemical cells and batteries

ABSTRACT

Provided are negative electrode compositions for lithium-ion electrochemical cells that include metal oxides and polymeric binders. Also provided are electrochemical cells and battery packs that include electrodes made with these compositions.

RELATED APPLICATIONS

This is a divisional application which claims priority to applicationSer. No. 12/129,141, filed May 29, 2008, which is now U.S. Pat. No.8,034,485, the disclosure of which is herein incorporated by referencein its entirety.

FIELD

Provided are negative electrode compositions for lithium-ionelectrochemical cells that include metal oxides and polymeric binders.Also provided are electrochemical cells and battery packs that includeelectrodes made with these compositions.

BACKGROUND

Powdered metal oxides of main group elements and conductive powders suchas carbon black have been used to make negative electrodes forlithium-ion cells in a process that involves mixing the powdered activeingredients with a polymeric binder such as polyvinylidene fluoride. Themixed ingredients are prepared as a dispersion in a solvent for thepolymeric binder, and coated onto a metal foil substrate, or currentcollector. The resulting composite electrode contains the powderedactive ingredient in the binder adhered to the metal substrate.

Polymers, such as polyvinylidene fluoride, have been used as binders formetal, metal alloy, metal oxide and graphite-based lithium-ion cellelectrodes. However, the first cycle irreversible capacity loss in theresulting cells can be unacceptably large, e.g., as large as 300 mAh/gor more for an electrode based on a powdered metal oxide material. Inaddition the capacity loss may be unacceptably large, e.g. as large as70% capacity loss or more in 50 cycles for an electrode based on apowdered metal oxide material.

SUMMARY

In view of the foregoing, we recognize that there is a need forelectrodes that undergo reduced first cycle capacity loss (irreversiblecapacity loss) and reduced capacity fade. In addition there is a needfor electrodes that have high thermal stability and improved safetycharacteristics.

In one aspect, provided is an electrode composition for a negativeelectrode that includes a powdered material and a polymeric binder,wherein the powdered material includes a non-intercalating metal oxide,wherein the metal oxide is capable of undergoing lithiation anddelithiation, and wherein the polymeric binder includes at least one ofa polyacrylic acid, a lithium polyacrylate, or a polyimide.

In another aspect, provided is an electrode composition for a negativeelectrode that includes a powdered material and a polymeric binderwherein the powdered material includes an intercalating metal oxide,wherein the metal oxide is capable of undergoing lithiation anddelithiation, and wherein the polymeric binder includes a lithiumpolyacrylate.

Other embodiments include electrochemical cells that incorporate one ormore of the provided negative electrodes and battery packs that includeat least one of the provided electrochemical cells. Additionalembodiments include electronic devices that include the providedelectrochemical cells or battery packs.

The use of the provided negative electrode materials and electrodes,electrochemical cells, and battery packs made therefrom can providereduced irreversible capacity and fade. The irreversible first cyclecapacity loss in these electrodes can be significantly decreased byforming the electrode using provided binders. The provided binders canbe used to prepare electrodes and cells that exhibit decreased firstcycle irreversible capacity loss compared to electrodes or cells madewith conventional polymeric binders.

In this application:

“a”, “an”, and “the” are used interchangeably with “at least one” tomean one or more of the elements being described;

“active” refers to a material that can undergo lithiation anddelithiation;

“charge” and “charging” refer to a process for providing electrochemicalenergy to a cell;

“delithiate” and “delithiation” refer to a process for removing lithiumfrom an electrode material;

“discharge” and “discharging” refer to a process for removingelectrochemical energy from a cell, e.g., when using the cell to performdesired work;

“intercalating metal oxide” refers to a metal oxide that acts as a hostin which lithium can be electrochemically reversibly inserted andextracted at room temperature without significantly changing the crystalstructure of the starting host material;

“lithiate” and “lithiation” refer to a process for adding lithium to anelectrode material;

“metal oxide” refers to compounds that include at least one metalelement, having the formula MO_(x);

“negative electrode” refers to an electrode (often called an anode)where electrochemical oxidation and delithiation occurs during adischarging process;

“non-intercalating metal oxide” refers to a metal oxide that acts as ahost in which lithium can be electrochemically reversibly inserted andextracted at room temperature and during this process the structure ofthe host material is substantially changed; and

“positive electrode” refers to an electrode (often called a cathode)where electrochemical reduction and lithiation occurs during adischarging process;

The provided negative electrode compositions can provide compositionsuseful in the formation of negative electrodes for lithium-ion cellsthat, when combined with binders that include lithium polyacrylate,polyacrylic acid, or polyimide, can have one or more advantages such as,for example, higher capacities, decreased first cycle irreversible loss,and longer lifetime than those made using conventional processes. Ofparticular interest are negative electrode materials that includeintercalating or non-intercalating metal oxide with appropriate bindersas described herein.

The details of one or more embodiments are set forth in the accompanyingdescription below. Other features, objects, and advantages will beapparent from the description and from the claims.

DETAILED DESCRIPTION

In the following description it is to be understood that otherembodiments are contemplated and may be made without departing from thescope or spirit of the present invention. The following detaileddescription, therefore, is not to be taken in a limiting sense.

Unless otherwise indicated, all numbers expressing feature sizes,amounts, and physical properties used in the specification and claimsare to be understood as being modified in all instances by the term“about.” Accordingly, unless indicated to the contrary, the numericalparameters set forth in the foregoing specification and attached claimsare approximations that can vary depending upon the desired propertiessought to be obtained by those skilled in the art utilizing theteachings disclosed herein. The use of numerical ranges by endpointsincludes all numbers within that range (e.g. 1 to 5 includes 1, 1.5, 2,2.75, 3, 3.80, 4, and 5) and any range within that range.

Provided is an electrode composition for a negative electrode thatincludes a powdered material and a polymeric binder, wherein thepowdered material includes a non-intercalating metal oxide, wherein themetal oxide is capable of undergoing lithiation and delithiation, andwherein the polymeric binder includes at least one of a polyacrylicacid, a lithium polyacrylate, or a polyimide. The provided electrodecompositions include a non-intercalating metal oxide. Anon-intercalating metal oxide is a metal oxide into which lithium can bereversibly inserted and extracted electrochemically at room temperatureand during this process the structure of the material is substantiallychanged. That is, the atomic structure of the metal oxide-containingmaterial before lithium insertion and during lithium insertion isdifferent. Crystalline, non-intercalating metal oxides can betransformed to a composite of nano-sized metal grains and nano-sizedLi₂O grains during lithium insertion. Examples of usefulnon-intercalating metal oxide materials include Fe₂O₃, CoO, CO₃O₄, NiO,CuO, MnO, and LiFeO₂. The provided electrode composition can alsocomprise at least one of an oxide of titanium, vanadium, chromium,manganese, iron, cobalt, nickel, copper, zinc, molybdenum, niobium, ortungsten.

For an intercalating metal oxide, the atomic structure of the materialbefore lithium insertion and after a cycle of lithium insertion and fulllithium removal are essentially the same. Furthermore during the lithiuminsertion/removal process the structure of the host material isunchanged, apart from lattice distortions. Examples of intercalatingmetal oxide negative electrode materials include LiVO₂, Li₄Ti₅O₁₂, TiO₂,WO₂, and MoO₂. Such materials can be improved in performance by dopingwith appropriate elements. For instance the capacity of LiVO₂ electrodescan be improved substantially by replacing some of the vanadium withother elements, as described in U.S. Pat. Publ. Nos. 2005/0079417,2005/0164090, and 2006/0088766 (all Kim et al.). For the purposes ofthis In another aspect, provided is an electrode composition for anegative electrode that includes a powdered material and a polymericbinder wherein the powdered material includes an intercalating metaloxide, wherein the metal oxide is capable of undergoing lithiation anddelithiation, and wherein the polymeric binder includes a lithiumpolyacrylate. An intercalating metal oxide is a metal oxide in whichlithium can be reversibly inserted and extracted electrochemically atroom temperature without significantly changing the atomic structure ofthe starting host material. In this disclosure, compositions writtenstoichiometrically such as Li₄Ti₅O₁₂, TiO₂, WO₂, and MoO₂ include dopedvarieties, such as Li_(1.1)V_(0.85)Mo_(0.05)O₂ (in which some of thevanadium has been replaced with molybdenum and lithium).

Exemplary powdered material can have a maximum length in one dimensionthat is no greater than 60 μm, no greater than 40 μm, no greater than 20μm, or even smaller. The powders can, for example, have a maximumparticle diameter that can be submicron (i.e., nanoparticulate), atleast 1 μm, at least 2 μm, at least 5 μm, at least 10 μm or even larger.For example, suitable powders often have a maximum dimension of 1 μm to60 μm, 10 μm to 60 μm, 20 μm to 60 μm, 40 μm to 60 μm, 1 μm to 40 μm, 2μm to 40 μm, 10 μm to 40 μm, 5 μm to 20 μm, or 10 μm to 20 μm. Thepowdered materials can contain optional matrix formers within powderparticles.

Exemplary powdered materials useful for making negative electrodes ofthis invention include metal oxide powders that include vanadium such asthose described in U.S. Pat. Publ. Nos. 2005/0079417, 2005/0164090, and2006/0088766 (all Kim et al.); and U.S. Pat. Publ. No. 2007/0166615(Takamuku et al.); metal oxide powders that include titanium such asthose described in 2007/0298321 (Larbi et al.) and U.S. Pat. No.6,489,062 (Shunji et al.); metal oxide powders that include molybdenumas those described in U.S. Pat. No. 6,489,062 (Shunji et al.); metaloxide powders that include niobium as those described in U.S. Pat. No.5,015,547 (Koshiba et al.); metal oxide powders that include molybdenumor tungsten such as those described in J. Electrochem. Soc., 134(3), pg.638-41 (1987) (Auborn et al.); metal oxide powders that include iron orcobalt such as those described in J. Electrochem. Soc. 148, pg. A576(2001) (Obrovac et al.) combinations thereof and other powderedmaterials that will be familiar to those skilled in the art.

Powdered alloy particles can include a conductive coating. For example,a particle that contains a metal oxide can be coated with a layer ofconductive material (e.g., with the metal oxide composition in theparticle core and the conductive material in the particle shell).Suitable conductive materials include, for example, carbon, copper,silver, or nickel.

Exemplary powdered oxide anode materials can be prepared by any knownmeans, for example, by heating precursor materials in a furnace,typically at temperatures above 300° C. The atmosphere during theheating process is not limited, typically the atmosphere during theheating process can be air, an inert atmosphere, a reducing atmospheresuch as one containing hydrogen gas, or a mixture of gases. Theprecursor materials are also not limited. Suitable precursor materialscan be one or more metal oxides, metal carbonates, metal nitrates, metalsulfates, metal chlorides or combinations thereof. Such precursormaterials can be combined by grinding, mechanical milling, precipitationfrom solution, or by other methods known in the art. The precursormaterial can also be in the form of a sol-gel. After firing, the oxidescan be treated with further processing, such as by mechanical milling toachieve an amorphous or nanocrystalline structure, grinding and particlesizing, surface coating, and by other methods known in the art.Exemplary powdered oxide anode materials can also be prepared bymechanical milling of precursor materials without firing. Powdered oxidematerials prepared in this way often have a nanocrystalline or amorphousmicrostructure. Suitable milling can be done by using various techniquessuch as vertical ball milling, horizontal ball milling, or other millingtechniques known to those skilled in the art.

The electrode composition can contain additives such as will be familiarto those skilled in the art. The electrode composition can include anelectrically conductive diluent to facilitate electron transfer from thepowdered material to a current collector. Electrically conductivediluents include, but are not limited to, carbon (e.g., carbon black fornegative electrodes and carbon black, flake graphite and the like forpositive electrodes), metal, metal nitrides, metal carbides, metalsilicides, and metal borides. Representative electrically conductivecarbon diluents include carbon blacks such as SUPER P and SUPER S carbonblacks (both from MMM Carbon, Belgium), SHAWANIGAN BLACK (ChevronChemical Co., Houston, Tex.), acetylene black, furnace black, lampblack, graphite, carbon fibers, single-walled carbon nanotubes,multiple-walled carbon nanotubes, and combinations thereof.

The electrode composition can include an adhesion promoter that promotesadhesion of the powdered material or electrically conductive diluent tothe binder. The combination of an adhesion promoter and binder can helpthe electrode composition better accommodate volume changes that canoccur in the powdered material during repeated lithiation/delithiationcycles. The provided binders can offer sufficiently good adhesion tometals, alloys and metal oxides so that addition of an adhesion promotermay not be needed. If used, an adhesion promoter can be made a part ofthe binder (e.g., in the form of an added functional group), can be acoating on the powdered material, can be added to the electricallyconductive diluent, or can be a combination of such measures. Examplesof adhesion promoters include silanes, titanates, and phosphonates asdescribed in U.S. Pat. No. 7,341,804 (Christensen).

Provided binders include lithium polysalts. Lithium polysalts includelithium polyacrylates (including polymethacrylates), lithiumpolystyrenesulfonates, and lithium polysulfonate fluoropolymers. Thelithium polysalts are available from the corresponding acrylic orsulfonic acids by neutralization of the acidic groups with basiclithium. Commonly lithium hydroxide is used to neutralize acid groups.It is also within the scope of this application to replace othercations, such as sodium, with lithium by ion exchange. For example, anion exchange resin such as SKT10L (available from Mitsubishi ChemicalIndustries under the trade name, DIANION), can be used to exchangesodium ion for lithium ion.

While not being bound by theory, it is believed that lithium polysaltscan coat powdered active materials and form a layer which is ionicallyconductive. Since lithium-ion electrochemical cells depend upon lithiumion conductivity this enhances the ability of electrodes made with thesebinders to have extended life and reduced fade. Additionally, it isbelieved that the provided lithium polysalts coat the powdered activematerials thinly enough that some electrical conductivity is maintained.Finally, it is believed that the lithium polysalts can suppress theformation of insulating SEI (solvent electrolyte interface) layers thatare known by those skilled in the art to lead to premature lithium-ionelectrode failure on repeated cycling.

The lithium polyacrylate binders include at least about 50 mole %, atleast about 60 mole %, at least about 70 mole %, at least about 80 mole%, at least about 90 mole %, or even more, of lithium based upon themolar equivalents of acidic groups (on the ends or on pendant groups) ofthe acid from which the polysalt is derived. Acidic groups that can beneutralized include carboxylic acid, sulfonic acid, phosphonic acid, andany other acidic group that has one proton to exchange that are commonlyfound on polymers. Examples of commercial materials that are useful inthis invention include perfluorosulfonic acid polymers such as NAPHION(available from DuPont, Wilmington, Del.), and thermoplastic ionomericpolymers such as SURLYN (also from Dupont). Other materials of interestinclude lithium polyimides such as those described in U.S. Pat. No.6,287,722 (Barton et al.).

Lithium polyacrylate can be made from poly(acrylic acid) that isneutralized with lithium hydroxide. In this application, poly(acrylicacid) includes any polymer or copolymer of acrylic acid or methacrylicacid or their derivatives where at least about 50 mole %, at least about60 mole %, at least about 70 mole %, at least about 80 mole %, or atleast about 90 mole % of the copolymer is made using acrylic acid ormethacrylic acid. Useful monomers that can be used to form thesecopolymers include, for example, alkyl esters of acrylic or methacrylicacid that have alkyl groups with 1-12 carbon atoms (branched orunbranched), acrylonitriles, acrylamides, N-alkyl acrylamides,N,N-dialkylacrylamides, hydroxyalkylacrylates, maleic acid,propanesulfonates, and the like. Of particular interest are polymers orcopolymers of acrylic acid or methacrylic acid that are watersoluble—especially after neutralization or partial neutralization. Watersolubility is typically a function of the molecular weight of thepolymer or copolymer and/or the composition. Poly(acrylic acid) is verywater soluble and is preferred along with copolymers that containsignificant mole fractions of acrylic acid. Poly(methacrylic) acid isless water soluble—particularly at larger molecular weights.

Homopolymers and copolymers of acrylic and methacrylic acid that areuseful as binders can have a molecular weight (M_(w)) of greater thanabout 10,000 g/mole, greater than about 75,000 g/mole, or even greaterthan about 450,000 g/mole, or even higher. The homopolymers andcopolymer that are useful in this invention have a molecular weight(M_(w)) of less than about 3,000,000 g/mole, less than about 500,000g/mole, less than about 450,000 g/mole, or even lower. Carboxylic acidicgroups on the polymers or copolymers can be neutralized by dissolvingthe polymers or copolymers in water or another suitable solvent such astetrahydrofuran, dimethylsulfoxide, N,N-dimethylformamide, or one ormore other dipolar aprotic solvents that are miscible with water. Thecarboxylic acid groups (acrylic acid or methacrylic acid) on thepolymers or copolymers can be titrated with an aqueous solution oflithium hydroxide. For example, a solution of 34 wt % poly(acrylic acid)in water can be neutralized by titration with a 20 wt % solution ofaqueous lithium hydroxide. Typically, 50% or more, 60% or more, 70% ormore, 80% or more, 90% or more, 100% or more, 107% or more of thecarboxylic acid groups are lithiated (neutralized with lithiumhydroxide) on a molar basis. When more than 100% of the carboxylic acidgroups have been neutralized this means that enough lithium hydroxidehas been added to the polymer or copolymer to neutralize all of thegroups with an excess of lithium hydroxide present.

Polymeric binders that can also be included in embodiments of theprovided electrode compositions include polyimide binders. Usefulpolyimide binders include aromatic, aliphatic or cycloaliphaticpolyimide binders. Conventional polyimide binders can be prepared byreacting an aromatic dianhydride and a diamine This reaction leads tothe formation of an aromatic polyamic acid, and subsequent chemical orthermal cyclization leads to the polyimide. Aliphatic or cycloaliphaticpolyimide binders can also be used in some embodiments of the providedelectrode compositions comprises repeating units having the formula:

where R₁ is aliphatic or cycloaliphatic and R₂ is aromatic, aliphatic,cycloaliphatic or a combination thereof. The polyimide binders aredisclosed, for example, in U.S. Pat. Publ. No. 2006/099506 (Krause etal.).

The provided binders can be mixed with other polymeric materials to makea blend of materials. This may be done, for example, to increase theadhesion, to provide enhanced conductivity, to change the thermalproperties, or to affect other physical properties of the binder. Thebinders of this invention, however, can be non-elastomeric. Bynon-elastomeric it is meant that the binders do not contain substantialamounts of natural or synthetic rubber. Synthetic rubbers includestyrene-butadiene rubbers and latexes of styrene-butadiene rubbers. Forexample, the binders of this invention contain less than 20 weightpercent (wt %), less than 10 wt %, less than 5 wt %, less than 2 wt %,or even less of natural or synthetic rubber.

A variety of electrolytes can be employed in the disclosed lithium-ioncells. Representative electrolytes contain one or more lithium salts anda charge-carrying medium in the form of a solid, liquid, or gel.Exemplary lithium salts are stable in the electrochemical window andtemperature range (e.g. from about −30° C. to about 70° C.) within whichthe cell electrodes can operate, are soluble in the chosencharge-carrying media, and perform well in the chosen lithium-ion cell.Exemplary lithium salts include LiPF₆, LiBF₄, LiClO₄, lithiumbis(oxalato)borate, LiN(CF₃SO₂)₂, LiN(C₂F₅SO₂)₂, LiAsF₆, LiC(CF₃SO₂)₃,and combinations thereof. Exemplary charge-carrying media are stablewithout freezing or boiling in the electrochemical window andtemperature range within which the cell electrodes can operate, arecapable of solubilizing sufficient quantities of the lithium salt sothat a suitable quantity of charge can be transported from the positiveelectrode to the negative electrode, and perform well in the chosenlithium-ion cell. Exemplary solid charge carrying media includepolymeric media such as polyethylene oxide, polytetrafluoroethylene,polyvinylidene fluoride, fluorine-containing copolymers,polyacrylonitrile, combinations thereof, and other solid media that willbe familiar to those skilled in the art. Exemplary liquid chargecarrying media include ethylene carbonate, propylene carbonate, dimethylcarbonate, diethyl carbonate, ethyl methyl carbonate, butylenecarbonate, vinylene carbonate, fluoroethylene carbonate, fluoropropylenecarbonate, γ-butylrolactone, methyl difluoroacetate, ethyldifluoroacetate, dimethoxyethane, diglyme (bis(2-methoxyethyl)ether),tetrahydrofuran, dioxolane, combinations thereof and other media thatwill be familiar to those skilled in the art. Exemplary charge carryingmedia gels include those described in U.S. Pat. Nos. 6,387,570 (Nakamuraet al.) and 6,780,544 (Noh). The charge carrying media solubilizingpower can be improved through addition of a suitable cosolvent.Exemplary cosolvents include aromatic materials compatible withlithium-ion cells containing the chosen electrolyte. Representativecosolvents include toluene, sulfolane, dimethoxyethane, combinationsthereof and other cosolvents that will be familiar to those skilled inthe art. The electrolyte can include other additives that will familiarto those skilled in the art. For example, the electrolyte can contain aredox chemical shuttle such as those described in U.S. Pat. Nos.5,709,968 (Shimizu), 5,763,119 (Adachi), 5,536,599 (Alamgir et al.),5,858,573 (Abraham et al.), 5,882,812 (Visco et al.), 6,004,698(Richardson et al.), 6,045,952 (Kerr et al.), and 6,387,571 (Lain etal.); and in U.S. Pat. Publ. Nos. 2005/0221168, 2005/0221196,2006/0263696, and 2006/0263697 (all to Dahn et al.).

The provided electrochemical cells can be made by taking at least oneeach of a positive electrode and a negative electrode as described aboveand placing them in an electrolyte. Typically, a microporous separator,such as CELGARD 2400 microporous material, available from Celgard LLC,Charlotte, N.C., can be used to prevent the contact of the negativeelectrode directly with the positive electrode. Electrochemical cellsmade with the provided negative electrodes and binders showed reducedirreversible capacity loss and less fade than similar cells containingnegative electrodes with conventional binders.

Positive electrodes useful in the provided electrochemical cells caninclude, for example, LiCO_(0.2)Ni_(0.8)O₂, LiNiO₂, LiFePO₄, LiMnPO₄,LiCoPO₄, LiMn₂O₄, and LiCoO₂; the cathode compositions that includemixed metal oxides of cobalt, manganese, and nickel such as thosedescribed in U.S. Pat. Nos. 6,964,828 and 7,078,128 (Lu et al.); andnanocomposite cathode compositions such as those described in U.S. Pat.No. 6,680,145 (Obrovac et al.). Other exemplary positive electrodes caninclude LiNi_(0.5)Mn_(1.5)O₄ and LiVPO₄F.

The provided cells can be used in a variety of devices, includingportable computers, tablet displays, personal digital assistants, mobiletelephones, motorized devices (e.g., personal or household appliancesand vehicles), instruments, illumination devices (e.g., flashlights) andheating devices. One or more of the provided electrochemical cells canbe combined to provide battery pack. Further details regarding theconstruction and use of rechargeable lithium-ion cells and battery packswill be familiar to those skilled in the art.

Objects and advantages of this invention are further illustrated by thefollowing examples, but the particular materials and amounts thereofrecited in these examples, as well as other conditions and details,should not be construed to unduly limit this invention.

EXAMPLES Preparation of Poly(Acrylic Acid) (PAA, Neutralized with LiOH)Solution

Starting material A: 15.258 g LiOH.H₂O (Sigma-Aldrich) was mixed with137.610 g distilled water using a magnetic stirrer. The formed LiOH.H₂Osolution was 9.98 wt % LiOH.

Starting material B: 25 wt % PAA solution (Alfa Aesar, M_(n) 240,000).

128.457 g of material A was added into 88.045 g material B. The mixturewas stirred overnight. The formed solution was 11 wt % PAA (100% Lisalt-all acid neutralized without excess) binder solution.

Electrode Fabrication Examples 1-7 and Comparative Examples 1-5

A coating composition of 80 wt % active material (AM), 12 wt % carbonblack and 8 wt % binder were used to fabricate negative electrodes.Active materials (AM) were tested include Fe₂O₃, FeO, CO₃O₄, and CoO.Ball-milled materials were processed as follows: 4 g of active materialpowder (either Fe₂O₃ powder or CO₃O₄ powder) was milled for 2 hrs underargon protection using a Spex 8000 high energy ball milling machine with12 mm diameter hardened stainless steel balls as the mixing media. Thecarbon black used was super S carbon black (SS) (MMM Carbon, Belgium).Binders used included poly(vinylidene fluoride) (PVDF), poly(acrylicacid) Li salt (PAA-100% neutralized), polyimide (PI), and sodiumcarboxymethyl cellulose (CMC). The compositions of the tested electrodesare shown in Table 1.

TABLE 1 Compositions of Electrodes of Examples 1-7 and ComparativeExamples 1-5 Active Carbon Example material (AM) black Binder 1 Fe₂O₃ SSPAA(-100% Li salt) 2 Fe₂O₃ ball-milled SS PAA(-100% Li salt) 3 Fe₂O₃ SSPI 4 Fe₂O₃ ball-milled SS PI 5 FeO SS PI 6 Co₃O₄ ball-milled SS PI 7 CoOSS PI Comparative 1 Fe₂O₃ SS PVDF Comparative 2 Fe₂O₃ SS CMC Comparative3 Fe₂O₃ ball-milled SS PVDF Comparative 4 Fe₂O₃ ball-milled SS CMCComparative 5 Co₃O₄ ball-milled SS PVDF

Electrode Preparation Examples 1-7 and Comparative Examples 1-5 Example1

0.592 g AM, 0.089 g SS, 0.538 g PAA (−100% Li salt) solution (11 wt %solution in water, made by the method mentioned above) and 1.389 g waterwere added into an egg-shaped hardened steel vial. The mixture wasshaken for one half hr at 500 shakes per minute using a low energy ballmill (modified Spex 8000 mill). The formed slurry was then cast on acopper foil with a 75 μm high notch bar and dried at 90° C. in airovernight. Typical active material loading was 1.58 mg/cm².

Example 2

0.503 g AM, 0.075 g SS, 0.457 g PAA (100% Li salt) solution (11 wt %solution in water, made by the method mentioned above) and 1.313 g waterwere added into an egg-shaped hardened steel vial. The mixture wasshaken to form a slurry and then coated and dried as described inExample 1. Typical active material loading was 1.32 mg/cm².

Example 3

0.518 g AM, 0.077 g SS, 0.263 g PI solution (HD Micro PI2525, 19.6 solidwt % solution in NMP) and 1.400 g NMP were added into an egg-shapedhardened steel vial. The mixture was shaken to form a slurry and thencoated and dried as described in Example 1. Typical active materialloading was 1.38 mg/cm².

Example 4

0.608 g AM, 0.091 g SS, 0.310 g PI solution (HD micro PI2525, 19.6 solidwt % solution in NMP) and 1.545 g NMP were added into an egg-shapedhardened steel vial. The mixture was shaken to form a slurry and thencoated and dried as described in Example 1. Typical active materialloading was 1.45 mg/cm².

Examples 5-7

0.484 g AM, 0.073 g SS, 0.247 g PI solution (HD micro PI2525, 19.6 solidwt % solution in NMP) and 1.242 g NMP were added into an egg-shapedhardened steel vial. The mixture was shaken to form a slurry and thencoated and dried as described in Example 1. Typical active materialloading was 1.65 mg/cm².

Comparative Example 1

0.590 g AM, 0.088 g SS, 0.655 g PVDF solution (9 wt % solution of KYNAR461 in N-methylpyrrolidinone (NMP)) and 1.545 g NMP were added into anegg-shaped hardened steel vial. The mixture was shaken to form a slurryand then coated and dried as described in Example 1. Typical activematerial loading was 1.19 mg/cm².

Comparative Example 2

0.500 g AM, 0.075 g SS, 0.050 g CMC powder (Daicel CMC2200) and 2.485 gwater were added into an egg-shaped hardened steel vial. The mixture wasshaken to form a slurry and then coated and dried as described inExample 1. Typical active material loading was 1.00 mg/cm².

Comparative Example 3

0.515 g AM, 0.077 g SS, 0.572 g PVDF solution (9 wt % solution inN-methyl pyrrolidinone (NMP), NRC Canada) and 1.562 g NMP were addedinto an egg-shaped hardened steel vial. The mixture was shaken to form aslurry and then coated and dried as described in Example 1. Typicalactive material loading was 1.07 mg/cm².

Comparative Example 4

0.500 g AM, 0.075 g SS, 0.050 g CMC powder (Daicel CMC2200) and 2.565 gwater were added into an egg-shaped hardened steel vial. The mixture wasshaken to form a slurry and then coated and dried as described inExample 1. Typical active material loading was 0.94 mg/cm².

Comparative Example 5

0.484 g AM, 0.073 g SS, 0.247 g PI solution (HD micro PI2525, 19.6 solidwt % solution in NMP) and 1.242 g NMP were added into an egg-shapedhardened steel vial. The mixture was shaken to form a slurry and thencoated and dried as described in Example 1. Typical active materialloading was 1.65 mg/cm².

Test Cell Preparation for Examples 1-7 and Comparative Examples 1-5

The electrodes described above served as a working electrode in a2325-type coin cell using a lithium foil (FMC) disk as a counter andreference electrode. Two layers of microporous polypropylene (PP)separator (CELGARD 2500) were used for each coin cell. The electrolyteused was 1 M LiPF₆ (Stella, Japan) in a mixed solution of 90 wt %ethylene carbonate (EC):diethyl carbonate (DEC) (volume ratio 1:2, GrantChemical Ferro Division) and 10 wt % fluoroethylene carbonate (FEC,Fujian Chuangxin, China). The coin cells were assembled and crimpedclosed in an argon-filled glove box. The cells were cycled at C/20 forthe first two cycles, followed by cycling at C/5 for the rest of thecycles. C-rate was calculated based on a specific capacity of 1007mAh/g. Cycling results (mAh/g vs. cycle number) are listed in Table 2:

TABLE 2 Cycling Results of Electrodes of Examples 1-7 and ComparativeExamples 1-5 First Cycle 50th Cycle Delithiation Delithiation ExampleCapacity (mAh/g) Capacity (mAh/g) 1 Cell #1(#2) Cell #1(#2) 877(960)727(848) 2 948(892) 732(717) 3  994(1007) 813(844) 4 1052(1056) 852(866)5 771(748) 478(452) 6 741 726 7 782(773) 588(581) Comparative 1 786(699)422(422) Comparative 2 864(864) 654(649) Comparative 3 822(840) 513(516)Comparative 4 961(975) 738(322) Comparative 5 777(713) 638(587)

Synthesis of Li_(1.1)V_(0.85)Mo_(0.05)O₂ Examples 8 and ComparativeExample 6

Li_(1.1)V_(0.85)Mo_(0.05)O₂ was prepared by first grinding together byhand 4.500 g of V₂O₃ (Aldrich 98%), 2.871 g of Li₂CO₃ (Alfa Aesar 99.0%)and 0.507 g of MoO₃ (BDH Chemicals Ltd. 99.5%). The ground mixture wasthen placed in a graphite crucible and heated in a tube furnace underflowing argon gas for 12 hours at 1000° C.

Example 8

2.4 g Li_(1.1)V_(0.85)Mo_(0.50)O₂ prepared as described above, 0.36 gSS, 2.18 g PAA (100% Li salt) solution (11 wt % solution in water, madeby the method mentioned above) and 2.86 g water were added into anegg-shaped hardened steel vial. The mixture was shaken to form a slurryand then coated and dried as described in Example 1.

Comparative Example 6

2.58 g Li_(1.1)V_(0.85)Mo_(0.05)O₂ prepared as described above, 0.21 gSS, 2.33 g PVDF solution (9 wt % solution in N-methylpyrrolidinone(NMP), NRC Canada) and 0.5 g NMP were added into an egg-shaped hardenedsteel vial. The mixture was shaken to form a slurry and then coated anddried as described in Example 1.

Test Cell Preparation for Example 8 and Comparative Examples 6

The electrodes described above served as a working electrode in a2325-type coin cell using a lithium foil (FMC) disk as a counter andreference electrode. Two layers of microporous polypropylene (PP)separator (CELGARD 2500) were used for each coin cell. The electrolyteused was 1 M LiPF₆ (Stella, Japan) in a mixed solution of 90 wt %ethylene carbonate (EC):diethyl carbonate (DEC) (volume ratio 1:2, GrantChemical Ferro Division) and 10 wt % fluoroethylene carbonate (FEC,Fujian Chuangxin, China). The coin cells were assembled and crimpedclosed in an argon-filled glove box. The cells were cycled at C/20 ratebetween 2 V and 0.025 V. C-rate was calculated based on a specificcapacity of 300 mAh/g. Cycling results (mAh/g vs. cycle number) arelisted in Table 3:

TABLE 3 Cycling Results of Electrodes of Example 8 and ComparativeExample 6 First Cycle 50th Cycle Delithiation Delithiation ExampleCapacity (mAh/g) Capacity (mAh/g) 8 300.7 218.5 Comparative 6 125.9 9.1

Various modifications and alterations to this invention will becomeapparent to those skilled in the art without departing from the scopeand spirit of this invention. It should be understood that thisinvention is not intended to be unduly limited by the illustrativeembodiments and examples set forth herein and that such examples andembodiments are presented by way of example only with the scope of theinvention intended to be limited only by the claims set forth herein asfollows.

What is claimed is:
 1. An electrode composition for a negative electrodecomprising: a powdered material; and a polymeric binder, wherein thepowdered material includes an intercalating metal oxide, wherein themetal oxide is capable of undergoing lithiation and delithiation, andwherein the polymeric binder includes a lithium polyacrylate, andwherein the powdered material comprises LiVO₂ in which up to 15 molepercent of the V is replaced by a combination of lithium and molybdenum.2. A lithium-ion electrochemical cell comprising: a positive electrode,an electrolyte; and a negative electrode that comprises an electrodecomposition according to claim
 1. 3. A battery pack comprising at leastone lithium-ion electrochemical cell according to claim
 2. 4. Anelectronic device comprising a battery pack according to claim
 3. 5. Anelectrode composition for a negative electrode comprising: a powderedmaterial; and a polymeric binder, wherein the powdered material includesan intercalating metal oxide, wherein the metal oxide is capable ofundergoing lithiation and delithiation, and wherein the polymeric binderincludes a lithium polyacrylate, and wherein the powdered materialcomprises at least one of LiVO₂, Li_(1.1)V_(0.85)Mo_(0.05)O₂, Li₄Ti₅O₁₂,TiO₂, WO₂, or MoO₂.
 6. A lithium-ion electrochemical cell comprising: apositive electrode, an electrolyte; and a negative electrode thatcomprises an electrode composition according to claim
 5. 7. A batterypack comprising at least one lithium-ion electrochemical cell accordingto claim
 6. 8. An electronic device comprising a battery pack accordingto claim 7.